library(sf)
cong.map <- st_read("cong_map.shp")
states <- st_read("States_shapefile.shp")
states <- subset(states, !State_Code %in% c("AK","HI")) 

library(ggplot2)
ggplot() + 
  geom_sf(data = cong.map, linewidth = 0.6, color = "grey", fill = "#f2f2f2") +
  geom_sf(data = states, linewidth = 0.8, color = "black", fill = NA) +
  ggtitle("US 116th Congressional Districts") + 
  coord_sf()